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MR-44 Adapter - Voltage Reducing Converter

Type: Voltage reducing adapter kit

Contents: Kit contains 1 x MR-44 Adapter, 1 x 392 cell. Output Voltage: 1.35 V.

Diameter: 11.6 mm. Height: 5.4 mm. 

Price: 29.43 each. Postage and packing included.

Emulates: MR44, NR44, EPX675, PX675, H-C, KX675, HD675, HC, V675PX, RPX675, RM675, 1128MP.

The "Rolls Royce" solution to problem of the discontinued Mercuric Oxide MR44 and PX675. Our MR-44 Adapter has the outer dimensions of the PX675  mercury cell with a recess that takes the inexpensive and easily obtained silver oxide 392 cell. Buried within the MR-44 Adapter are micro electronics that drop the voltage from the 1.55 Volts put out by the silver oxide cell to the 1.35 Volts that your  camera was designed for.

No adjustment or modification to your camera is required. The MR-44 Adapter does not require activation or a supply of air. The MR-44 Adapter and silver oxide 392 cell has a significantly longer battery life than the zinc air WeinCELL MRB675 batteries.

MR-44 Adapters are a one time purchase, and will last a lifetime. Simply replace the expired silver oxide 392 cell with a fresh one.



The MR-44 Adapter is designed for low current and cannot be used in applications that exceed 200 micro amps. There are no known examples with this adapter though there are two examples involving the similar MR-9 Adapter where the metering and exposure system function perfectly, but the battery check lamp will not illuminate.

If you wish to measure the voltage from the MR-44 Adapter and silver oxide cell with a digital voltmeter, put a 10 KiloOhm resistance between the measurement terminals. This will allow sufficient current to flow to activate the voltage reducing circuitry. An analogue voltmeter will draw sufficient voltage to activate the voltage reducing circuitry.

Click here to purchase extra 392 cells.

We sometimes have genuine mercury PX675 cells available. Check here............

There are other possible mercury free replacements for a PX625, PX13 or MR9 cell, click on the links to find out more:

The least expensive PX675 replacement is the alkaline cell, the LR44 or PX76A. They fit perfectly but, as with all alkaline cells the voltage is not stable, it drifts down from 1.5V towards 1.35V (the voltage of the original Mercury cell) and then lower still. If you use the cell in a camera that needs a steady reference voltage, as the voltage is not steady throughout the useful life of the cells,  you need to constantly adjust how you compensate.

Because the 357 silver oxide cell produces a steady 1.55V, you are able to compensate for the higher voltage by a  fixed number of stops or by adjusting the ASA setting. There may be as many as two f-stops underexposure by a camera that uses 1.55v instead of the original 1.35v, but the compensation you require is constant.

Another PX675 replacement is a zinc air battery. The WeinCELL MRB675 is a custom zinc/air battery designed to replace banned mercury batteries.  WeinCELLs deliver the same 1.35 V voltage and stability of output as did the mercury PX675 batteries so there is no need to adjust your exposure. The WeinCELL MRB675 batteries last longer than hearing aid batteries, up to nine months. To achieve this longer life, the MRB675 uses a proprietary electrolyte and has only two small air holes, instead of the larger holes (some times as many as seven of them) found in standard hearing aid batteries.

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